(1) Field of the Invention
The present invention relates to the provision of an oxidation prevention coating on aluminum and particularly to the plating of aluminum. More specifically, this invention is directed to an intermediate alloy employed in the plating of aluminum and to apparatus for use in the hot and continuous plating of aluminum. Accordingly, the general objects of the present invention are to provide novel methods, materials and apparatus of such character.
(2) Description of the Prior Art
It is well known that, for many applications, aluminum can be substitued for copper. Because of the cost differential between aluminum and copper, such substitution is generally considered desirable. However, aluminum has the disadvantageous characteristic of being readily oxidizable. Accordingly, in order to enhance the utility of aluminum as a copper substitute, steps must be taken to reduce the oxidation thereof. The most commonly employed method of preventing oxidation of aluminum consists of plating with a layer of a material such as tin.
At the present time, electrolytic plating is the only process used with success for accomplishing a durable and effective bond between aluminum and tin or other oxidation preventing metal. However, taking energy consumption into account, electrolytic plating presents a serious financial inconvenience and in many cases the costs incident to electrolytic plating completely offset the economic advantages which would otherwise be gained from substitution of aluminum for copper.
Non-electrolytic processes for the hot and continuous plating of aluminum have been proposed and, in some cases, tested. Such continuous hot plating processes contemplate passing the aluminum through a molten bath of an oxidation preventing metal such as tin or a tin alloy. The previously proposed and tested continuous aluminum plating processes have afforded less than satisfactory results. Thus, the tin or other material plated onto aluminum during the previously attempted continuous hot plating processes has had a tendency to delaminate from the alumium.